DEM study of the effect of fines content on the small-strain stiffness of gap-graded soils

This letter examines the effect of fines content on the small-strain stiffness (G(0)) of gap-graded soils via the discrete element method (DEM). The G(0) values were obtained by DEM simulations of drained triaxial tests. Microscopic analysis reveals that the G(0) uniquely depends on the mechanical coordination number (CN) of the soils. Furthermore, modified CNs that consider coarse-coarse, coarse-fine and fine-fine contact in the sample are quantified, partially reflecting the contribution of each contact type to G(0). The results indicate that as fines content increases, the fines begin to participate in the force chains and their contribution to G(0) should be considered.